The invention relates to a single wheel suspension that is configured for a non-steerable driven wheel of a two track vehicle. The invention comprises two control arms, which extend, when viewed in a vertical projection, essentially in the longitudinal direction of the vehicle from a kinematic perspective and which can be pivoted in each case in an essentially vertical plane due to their mounting, wherein a wheel bearing, which carries the wheel, is fastened directly or indirectly to the first control arm; and the first control arm is supported with its end section on the vehicle body by way of a pendulum support, which extends at least approximately in the vertical direction in the as-designed position, or by way of an A-arm having a broadened base, and wherein the second control arm is supported, on the one hand, in an articulated manner directly or indirectly on the vehicle body with only one kinematic rotational degree of freedom and, on the other hand, is connected in an articulated manner to the first control arm between the wheel bearing and the attachment point of the pendulum support with only one kinematic rotational degree of freedom by a connecting element, representing a pivot axis, and wherein the first control arm is located with at least its section which extends from the wheel bearing to the connecting element with the second control arm, inside the space which is enclosed or described by a rim of the wheel. The wheel can be driven by a drive shaft and a gear mechanism which adjoins said drive shaft and is arranged at least partially inside the space enclosed or described by the rim of the wheel and which comprises at least two transmission stages, which are offset from each other in the axial direction of the wheel and formed by gear wheels.
Such a single wheel suspension is a combination of the subject matter disclosed in the international patent application, bearing the filing number PCT/EP2010/067478, which is not a prior publication, and the German patent application, bearing the official filing number DE102009038424.3, which also is not a prior publication. The entire content of the disclosure of each of the two patent applications is hereby explicitly incorporated in the present patent application by reference. However, in addition, it must be clarified how the concept that is used in the present patent application, i.e. the control arms extend essentially in the longitudinal direction of the vehicle from a kinematic perspective and can be pivoted in an essentially vertical plane, is to be construed. A control arm of the single wheel suspension according to the invention does not necessarily have to have the shape of the conventional wheel-guiding control arms of wheel suspensions, but can still act, nevertheless, when viewed kinematically, as a control arm and can exhibit the defined potential movements. In any event a “straight line approximation” can be defined for such a control arm in a kinematic model. Then such a control arm has the described property, i.e. extends essentially in the longitudinal direction of the vehicle and can be pivoted in an essentially vertical plane. In this case the concept “essentially” can be treated as equivalent to the fact that the control arms or more specifically their “straight line approximation” in a kinematic model are inclined by not more than an angle in an order of magnitude of 6° to 10° relative to the longitudinal direction of the vehicle and that said control arms can be pivoted in a plane, which is inclined by not more than an angle in an order of magnitude from 6° to 10° relative to the vertical plane, due to their mounting. Furthermore, it must also be pointed out that the concept “in the as-designed position” denotes, as known to the person skilled in the art, the position of the wheel relative to the vehicle body for a maximally loaded vehicle when the vehicle is standing still.
Based on the aforesaid, the object is to provide an especially space-saving arrangement for such a single wheel suspension (=object of the present invention).
The solution to this problem lies in a single wheel suspension that is characterized in that the axis of rotation of a connecting shaft, which connects the second gear wheel (when view from the direction of the drive shaft) of the first transmission stage to the first gear wheel of the second transmission stage, coincides with the pivot axis, representing the connecting element of the two control arms. Advantageous embodiments and further developments are the content of the dependent claims.
The aforementioned characterizing features require very little installation space, because the said connecting shaft and the said connecting element can be arranged concentrically to each other due to the rotational axis of the connecting shaft being coincident with the pivot axis of the connecting element. That is, the connecting shaft can be configured, for example, as a hollow shaft having an interior, in which the connecting element runs. It goes without saying that the reverse arrangement is also possible. For example, it is also possible in the sense of an advantageous further development that the connecting element itself can form the connecting shaft in that the two control arms of the single wheel suspension can be pivoted about the axis of rotation or more specifically about the said pivot axis by suitable bearings and, hence, can be securely mounted on the connecting element or more specifically on the connecting shaft in the axial direction.
In applying the same principle, the axis of rotation of the said drive shaft can also coincide with the pivot axis of the second control arm, in which this second control arm is supported in an articulated manner on the vehicle body with only one kinematic rotational degree of freedom, so that the result is an additional saving of needed installation space. In particular, however, this feature permits the output shaft of a motor, in particular an electric motor, to be used more or less directly as a drive shaft without the interpositioning of a cardan element. In this case this motor can be fastened in an advantageous way on the body of the vehicle and, as a result, does not belong to the so-called unsprung mass. Even in the case that the rotational axis of the said drive shaft coincides with the pivot axis of the second control arm relative to the body of the vehicle, it is possible, in principle, that the corresponding respective control arm can be rotatably mounted on a shaft comprising one of these axes of rotation, just as in the case that the pivot axis of one of the two control arms coincides with an axis of rotation of the gear mechanism or with an axis of rotation of a transmission stage of said gear mechanism. At a minimum, however, the said shaft can extend concentrically to and inside a hollow structure or a hollow component, on which in turn the control arm is mounted, as required.
The first control arm that carries the wheel bearing is located with at least its section which extends from the wheel bearing to the connecting element with the second control arm, inside the space which is enclosed or described by a rim of the wheel. At variance with the said German patent application DE102009038424.3, the gear mechanism is arranged (only) at least partially inside the wheel. In this case the expression “inside the wheel” should be treated as equivalent to the space, i.e. the so-called cavity of the wheel, which is enclosed or described or more specifically limited by the rim of the wheel. This cavity of the wheel or the rim is defined, when viewed in a projection perpendicular to the pivot axis of the wheel, by the inside wall, which faces the pivot axis and is associated with the rim well, which extends in essence parallel to the pivot axis of the wheel, as well as by the so-called wheel disk, which is typically located in the region of the wheel exterior that faces away from the body of the vehicle, and the other edge plane of the rim that faces the body of the vehicle and that stands, just like the wheel disk, perpendicular on the pivot axis of the wheel. Therefore, when viewed in both a projection perpendicular to the pivot axis of the wheel and also in a lateral projection in the direction of the pivot axis of the wheel, the first control arm is located with at least its said section, which extends from the wheel bearing as far as to the connecting element with the second control arm, inside the said cavity; this also applies to at least one part of the gear mechanism. The result is a space-saving arrangement, wherein the first control arm can project with that section to which the said pendulum support or the said A-arm with a broadened base is joined, beyond the space which is enclosed or described by the rim, because this pendulum support or the said A-arm is located at least partially outside the space that is enclosed or described by the wheel rim, so that said pendulum support or said A-arm can be supported in turn on the body of the vehicle. If, as stated above, the first control arm projects with its section which is joined to the pendulum support or the like beyond the space that is enclosed or described by the wheel rim, this control arm cannot extend completely more or less in the longitudinal direction of the vehicle as a concrete component. For this reason the corresponding orientation of this control arm is recited in the claims only from a kinematic perspective. Furthermore, this first control arm is configured in a manner similar to a wheel carrier in the said international patent application PCT/EP2010/067478, which shows one possible concrete rendering of a single wheel suspension according to the present invention; however, in contrast this first control arm does, in fact, extend with its section which extends from the wheel bearing to the connecting element with the second control arm, essentially in the longitudinal direction of the vehicle when viewed from a kinematic perspective.
The installation space requirement of a single wheel suspension according to the invention can be reduced even more, if, in addition to the first control arm, which is located in sections inside the wheel rim, the second control arm is also located in essence inside the space which is enclosed or described or more specifically limited by the wheel rim, at least in the as-designed position and at least in a projection in the direction of the pivot axis of the wheel and/or the gear mechanism with its two transmission stages. On the side of the wheel that faces the body of the vehicle, this type of single wheel suspension does not need any additional installation space, with the exception of the said pendulum support or the said A-arm with a broad support base, which extends essentially in the transverse direction of the vehicle, as well as with the exception of the associated section of the first control arm and the support of the pendulum support or the said A-arm on the body of the vehicle as well as with the exception of the drive shaft that extends to the gear mechanism, so that the chassis or rather the body of the vehicle has ample installation space on the inside of the wheel that faces the body of the vehicle.
The aforementioned international application PCT/EP2010/067478 discloses that the pivot axis of the articulated connection between the first control arm and the second control arm can be slightly inclined relative to the horizontal plane (when viewed in the longitudinal direction of the vehicle) and/or relative to the transverse direction of the vehicle (when viewed in a vertical projection) in the as-designed position. The same applies to a single wheel suspension according to the present invention, because, in this case, too, this said measure makes it possible to achieve a desired change in the wheel camber angle and/or the wheel toe-in angle in connection with a vertical compression movement or decompression movement of the wheel. At least in the case of a substantial inclination of said pivot axis or rather the corresponding connecting element, the said gear mechanism comprising the said connecting shaft that coincides with this pivot axis should be adapted as required and, thus, consequently exhibits bevel gears, i.e. gears with an engagement surface in the shape of a cone, in this region. In the case of a preferred embodiment of the gear wheels as toothed gears, at least the first gear wheel of the second transmission stage, optionally also the second gear wheel, which is arranged on the same connecting shaft and is assigned to the first transmission stage, is designed as a bevel gear. It goes without saying that additionally it is also possible to design the additional gear wheels of the said gear mechanism as bevel gears. Furthermore, the second gear wheel of the second transmission stage can be designed preferably as a gear wheel with internal teeth, since a high transmission ratio in these two transmission stages can be achieved in a design that is optimized with respect to the installation space.
According to an advantageous further development of the present invention, at least one of the control arms is designed at least in sections in the manner of a housing, inside which the two gear wheels of a transmission stage are arranged. For the control arm this quasi box-like design provides high strength and minimizes the required installation space, because the gear wheels are arranged in the cavity of such a control arm, which is designed, for example, in the manner of a box; and the said housing protects the gear wheels from getting dirty and against the loss of lubricant into the surrounding area.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.